firstname.lastname@example.org wrote: > The specs of TI's SN75160B and SN75161B say a 1.7 K resistor plus a diode > for every output pin. Less then I thought :( > (5 - 0.6) / 1700 = 2.6 mA. So 6 devices shouldn't be a problem Hmm. I'm having some problems, though; I intended to use P0 for the 8 datalines, but even *reading* them completely crashes the bus, and often even resets the 8051. Very odd; P0 is a honest-to-heart open-collector thing (doesn't even have internal pull-ups). Hmm. Unless it's configured as push-pull for some obscure reason. Anyway; I now use P2 for the datalines, and that seems to be working like a charm. Stretching the timing of the bus works like a charm :) By the way, does anybody know when ATN is valid (or to be more precise: when it is *no longer* valid)? > > Programming a 8751 isn't really difficult. I have the specifications > > floating somewhere on my desk at Philips. Interested in a copy? > > Unfortunally it seems I don't have a 8751 although I still believe I have > at least one (but where ???). 8751's are "common as muck". Hfl 5,-- at Display electronica (and you actually get a 8752, which has more RAM and timers..) > On the other hand I found some 8741's, 8742's, 8748's and 8749's. I have > the Philips databook IC14 which contains info about the 8048 and 8049. But > NOT how to program them. I also have some 8048's but have no idea how to > find out if they are programmed or not. Hmm. I might be able to find this info as well; Philips's intranet is a *nightmare* though. > AFAIK I don't have anything about the 8741 and 8742. If you have any info > on these, I would be glad if you could help me with the specs of these, > please. At second thought, I might have that particular info at home. I collected a few databooks a few weeks ago, which I haven't really checked yet.. > I know the ML for these and the 8x51 differ but that shouldn't be a problem > if you would be so kind to donate the sources. I'll try to keep that in mind when implementing the IEC-part of the device; 8041-derivates have much simpler timers and all :( I don't know the 8041 quite well, but I seem to recall that it only had one (external) interrupt line. The 8051 has two of them, and I intended to use both of them (so that I can simply see if I got an 'IEC-ATN' or an 'IEEE' one :) > Looking for the 8751 I bumped in something else from the time I worked at > NatLab: two 8051 PODs, a V85C552 and a V85C582. Interested? You lost me somehwere; what's a POD? It sounds like In-cicuit emulators somehow. > I also found a loose 80552 which reminded me I have an Elektuur-card > equiped with this controller. IMHO this one could be used as well. I only > hope I have enough I/O-pins left for the interface self is this card is > equiped with an EPROM and SRAM. Hmm. I don't have my IC20-handbook at hand, but didn't the 552 have *6* I/O ports? Shouldn't be much of a problem, really. I'm not certain external RAM is really required; I haven't used a single byte of Data-space up to now (save stack) > > It would be a shame if the connection between the PET and the 4040 would > > be slowed down because of the 1541.. > > You would loose some time in the initial phase where all devices have to > check if the given devicenumber is theirs. It shouldn't slow down the > actual data transfers. You're absolutely right. > For IEEE you need 8 datalines and 6 controllines (REN and SQR not needed), > for IEC only three: DATA, CLK and ATN. RESET is covered by IFC. That makes > 17. Two for simple RS232 makes 19. Five left which enables you 8K of EPROM. > Which is a lot, I thought. That's right :) > > Maybe not; maybe I can abuse the UART for that.. > > Very smart indeed, petje af :) I'm not quite sure if it will be worth the effort; the 8051's UART can't be programmed very accurately at "high" bitrates, and I came up with a good use for the UART - My mac is still missing some way of accessing CBM-drives; it might be a nice idea to implement something like 'IEEE-over-RS232' :) > But if RS232 is possible, why not. I programmed more then just a little bit > 8051 ten years ago. (the above Elektuur 80552 I used for an electronic > ignition for a VW Beetle with on-the-fly tuning while driving it on a > testbank) If I remembered well, the RS232 communication, once started, > didn't need any further attention. Well, it only has a 1-byte "FIFO".. Ah well - I'll get back to it next monday; I'm going away for a weekend. Funny how these things always collide ;) Martijn.  Which is a bit of a nuisance; due to a bug^Wfeature of the 89c81Rx+ processors, pins P2.6 and P2.7 *must* be floating when doing in-circuit programming, which means that I have to disconnect the IEEE bus now :(. P3 got a 'stuck' bit somewhere (and it got the RS232 interface on it), so that isn't useful anyway :( -- Martijn van Buul - Pino@dohd.org - http://www.stack.nl/~martijnb/ Geek code: G-- - Visit OuterSpace: mud.stack.nl 3333 Kees J. Bot: The sum of CPU power and user brain power is a constant. - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail email@example.com.
Archive generated by hypermail 2.1.1.